It's like watching someone play Sim City on fast forward, but for real cities.

Calgary-based real estate company Cube Cities has put together a series of 3-D animations that offer a mesmerizing look at the development of the modern cityscapes of New York, Chicago, San Francisco, Calgary, and Toronto. The videos overlay developer-reported data on construction dates on 3-D mapping technology from Google Earth. So you can watch, for example, as the 1970s construction boom transforms Toronto.

Cube Cities is a relatively new company that seems to be focused on combining commercial real estate listings with Google Earth visualizations, in an effort to provide customers with a better idea of how prospective office space fits into a city's landscape. After signing up, you can zoom around and get a sense of, say, the views overlooking the Chicago River from the 40th floor of a specific skyscraper.

Developers used the video project to play around with representation models, so each of the videos use slightly different methods to indicate new buildings. In a particularly cool effect, the San Francisco animation begins with clear outlines of the current skyline, and viewers watch as the phantom city turns solid as time moves forward.

Thanks to vast amounts of publicly available development data in New York, the Midtown Manhattan animation offers even more detail. Beginning in the 1950s, buildings are color-coded by how they're mainly used (blue for office, purple for hotels, and green for residential).

Cube Cities CEO Greg Angevine says that the animations grew out of brainstorming other ways that the company could present its data to users beyond real estate customers. "3-D mapping is coming, but it's not really very accessible yet," Angevine says. "That creates a canvas for us."